Study: Do Low Carb Diets Actually Increase Risk of Heart Disease?

A new meta-analysis pooled eight high quality studies to try and answer some tricky questions around low carb diets.

A new meta-analysis of eight high quality, randomized controlled trials published in Nutrition Reviews aims to help answer the question of whether or now low carb diets increase the risk of heart disease.(1)

Restricting carbohydrates is a popular intervention for helping people to lose weight. Yes, limiting the one that’s the most prevalent in the Standard American Diet will likely lower one’s overall intake of calories, but some research has also found that low carb diets lower the risk of heart disease.(2)(3)

[Read more: Is a Low Carb Diet a Good Idea for Athletes?]

Nonetheless, concerns persist that increasing one’s fat intake can increase a risk for heart disease, especially since low carb diets usually don’t limited saturated fat. When it comes to cholesterol, research is conflicting, with some studies finding an increase in LDL cholesterol (that’s usually called the “bad” cholesterol), some finding no effect, and others finding a decrease.(4)(5)(6)

beef steak

The new study tried to pool the most high quality studies: only randomized controlled trials of at least 100 overweight or obese people, and they needed to last a good six months. We don’t know how much of the fat intake was saturated, or unsaturated. It found that when compared with low fat diets, low carb diets significantly increased both LDL (“bad”) and HDL (“good”) cholesterol.

But the difference was small — the LDL increased by 0.07 mmol/L, which is probably clinically insignificant and amounts to about a 1.5% increase in short term risk. When that’s combined with the increase in HDL, which lowers the risk of cardiovascular disease, this meta-analysis suggested there may not be a real increase in risk at all, though we should keep in mind the analysis isn’t taking into account other risk factors, according to a review published in the Research Digest.

Those other risk factors for CVD include oxidization — oxidizing LDL makes it more pathogenic — so the participants’ oxidative status and levels of inflammation could significantly affect how much of an issue that LDL is.

This is yet another reason why one should take exercise, nutrient intake, and lifestyle factors into account when trying to manage the risk of heart disease.

[Learn more about fighting inflammation with our list of the best Omega-3 supplements on the market!]

casserole vegetables

Note that this meta-analysis isn’t definitive and that research remains conflicting as to the pros and cons of low carb and low fat diets for managing heart disease risk. Overall food intake and food sources are also hugely important here as well, so be sure to look at this study in the context of one’s overall approach to health and weight management.

Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems.


  1. Gjuladin-Hellon T, et al. Effects of carbohydrate-restricted diets on low-density lipoprotein cholesterol levels in overweight and obese adults: a systematic review and meta-analysis. Nutr Rev. 2019 Mar 1;77(3):161-180.
  2. Foster GD, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003 May 22;348(21):2082-90.
  3. Hu T, et al. The low-carbohydrate diet and cardiovascular risk factors: evidence from epidemiologic studies. Nutr Metab Cardiovasc Dis. 2014 Apr;24(4):337-43.
  4. Bueno NB, et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr. 2013 Oct;110(7):1178-87.
  5. Naude CE, et al. Low carbohydrate versus isoenergetic balanced diets for reducing weight and cardiovascular risk: a systematic review and meta-analysis. PLoS One. 2014 Jul 9;9(7):e100652.
  6. Hu T, et al. Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2012 Oct 1;176 Suppl 7:S44-54.